Ecophysiology of the hydrothermal vent snail Ifremeria nautilei and barnacle Eochionelasmus ohtai manusensis, Manus Basin, Papua New Guinea: Insights from shell mineralogy and stable isotope geochemistry. (March 2018)

• Record Type: Journal Article
• Authors: Bojar, Ana-Voica; Lécuyer, Christophe; Bojar, Hans-Peter; Fourel, François; Vasile, Ştefan
• Is Part Of: Deep sea research. Volume 133(2018)
• Page Start: 49
• Page End: 58
• Publication Date: 2018-03
• Subjects: Manus Spreading Center -- Ifremeria nautilei -- Eochionelasmus ohtai manusenis -- Minor elements -- Weddellite -- Stable isotopic composition; Oceanography -- Periodicals; Océanographie -- Périodiques; 551.4605
• DOI: 10.1016/j.dsr.2018.02.002
• Languages: English
• ISSNs: 0967-0637

Abstract

Abstract: Deep-sea vent communities live on a limited area characterized by sharp physico-chemical (temperature, salinity, pH) gradients. Around the vent, the fauna is distributed accordingly, showing characteristic niche partitioning for different groups of animals. In this study we investigate shell microstructure, minor elements and stable isotope compositions of two groups of organisms such as a snail, Ifremeria nautilei, and a crustacean, Eochionelasmus ohtai manusensis. Both organisms occupy distinct niches within the same hydrothermal vent field of the Manus Basin, Western Pacific. Powder XRD and electron microbeam analysis of a polished cross-section indicate that the shells are composed of microcrystalline calcite, with distinct Na, Mg, Sr, and S element contents. For both specimens 20–30 µm large weddellite crystals were found. The δ 18 O profiles were obtained perpendicular to the growth increments of I. nautilei and E. o. manusensis calcitic shells. Those profiles reveal isotopic variations of 0.5 and 0.6‰, respectively for both intra- and inter-shell measurements. For E. o. manusensis, the Mg content suggests continuous shell growth during the year, both δ 18 O and Mg data supporting cyclical variation of temperature at vent site. The calculated temperatures at sites with I. nautilei and E. o. manusensis range from 17° to 21.5°C and from 2.1° to 7.2°C, respectively, showing a similar variability of 5–6 °C. The δ 13 C values of the Ifremeria calcitic shell range from 3‰ to 4.6‰ (V-PDB), the isotopic composition being 13 C-enriched relative to the surrounding inorganic pool. The δ 13 C values of the chitine layer covering the shell range from − 33 to − 31.1‰. The δ 13 C values of Eochionelasmus vary between 0‰ and 1‰, reflecting the surrounding inorganic DIC pool. Highlights: Shell structure and mineralogy of deep-sea vents species are investigated. Periodic fluctuations of minor elements along the growth lines of shell. Fluctuation of isotopic composition related to bottom currents and niche partitioning. Variable nutritional pathways during life time.